Sepsis with Kidney Injury in ICU Needs Different Tactics

Action Points

Explain to interested patients that this study suggests that acute kidney injury with sepsis is often seen in intensive care units and may represent a unique condition, with poorer prognosis than either nonseptic kidney injury or sepsis alone, that requires its own therapeutic approaches.

EDMONTON, Alberta, April 10 -- When sepsis and acute kidney injury combine, a common ICU phenomenon, the clinician may be facing a unique pathophysiological condition that requires different therapeutic approaches, researchers here said.

In a retrospective database analysis, acute kidney injury with sepsis -- dubbed septic AKI -- accounted for almost 12% of ICU admissions, according to Sean Bagshaw, M.D., of the University of Alberta, and colleagues.

Septic AKI also caused more severe illness and had worse outcomes than either sepsis alone or acute kidney injury alone, Dr. Bagshaw and colleagues said in the open-access journal Critical Care.

The finding comes from an analysis of the Australian New Zealand Intensive Care Society Adult Patient Database, which prospectively collected data from 57 intensive care units across Australia.

From 2000 through 2005, 120,123 patients were admitted to those ICUs for more than 24 hours, Dr. Bagshaw and colleagues found, including 33,375 with a sepsis-related diagnosis.

Early acute kidney injury, with or without sepsis, was seen in 43,395 patients, and about a third of those (32.4%) had a primary diagnosis of sepsis.

That works out to a cumulative rate of 11.7% for septic AKI of total ICU admissions, Dr. Bagshaw and colleagues reported.

Compared with either sepsis alone or kidney injury alone, patients with septic AKI had significantly:

greater acuity of illness, at P<0.0001.

lower blood pressure, at P<0.0001.

higher heart rates, P<0.0001.

worse pulmonary function measures by the ratio of arterial oxygen tension to fraction of inspired oxygen, again at P<0.0001.

greater acidemia, at P<0.0001.

and higher white cell counts, P<0.0001.

The researchers stratified patients by three of the RIFLE (Risk of renal failure, Injury to the kidney, Failure of kidney function) criteria based upon serum creatinine and urine output and found that septic AKI was also associated with greater severity of injury than non-septic AKI.

Specifically, 38.5% of septic AKI patients belonged to the risk category, 38.8% to the injury category, and 22.7% to the failure category, compared with 16.3%, 13.6%, and 6.3%, respectively, for the non-septic AKI patients.

Septic AKI was associated with significantly higher mortality than non-septic kidney injury or with sepsis alone.

Patients with septic AKI were:

60% more likely to die in the ICU than non-septic AKI patients (OR 1.60, 95% CI 1.5 to 1.7, P<0.001)

53% more likely to die in the hospital than non-septic AKI patients (OR 1.53, 95% CI 1.46 to 1.60, P<0.001)

More than three times as likely to die in the ICU as sepsis patients (OR 3.07, 95% CI 2.9 to 3.3, P<0.001)

Nearly three times as likely to die in hospital as sepsis patients (OR 2.93, 95% CI 2.8 to 3.1, P<0.001)

The findings, combined with previous studies, imply that "septic AKI may be distinct, may behave differently and may independently portend a worse prognosis," the researchers argued.

"We contend that these findings have relevance for the management of the septic patient with AKI," they said.

The authors noted several limitations to the study, including the fact that occurrence of AKI was estimated at or within the first 24 hours of ICU admission, which excluded ICU-acquired AKI. They did not measure creatinine clearance and used the MDRD equation to estimate baseline function.

In addition, they wrote "we were unable to describe the association of initial RIFLE category to other clinical outcomes such as the proportion of patients receiving renal replacement therapy, long-term survival, or renal recovery beyond hospital discharge. Thus, whether septic AKI contributes to downstream morbidity and mortality conditional on hospital survival remains likely but unknown."

The study was partly supported by the Austin Hospital Anaesthesia and Intensive Care Trust Fund. Dr. Bagshaw reported no conflicts.

Reviewed by Zalman S. Agus, MD Emeritus Professor University of Pennsylvania School of Medicine

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